THE FACE OF THE SKY FOR SEPTEMBER. 



Bv \V. SILVCKLETOX. F.K..\.S.. A.R.C.Sc. 



The Sun. — On the 1st the Sun rises at 5.13 and sets at 6.4S ; 

 on the 30th he rises at 5.58 and sets at 5.43. The Sun enters 

 the sign of Libra on the 24th at 4 a.m.. when autumn 

 commences. The equation of time is negligible on the 1st 

 and 2nd. hence these dates are convenient for the adjustment 

 of sun-dials, as only the longitude correction is needed. Sun- 

 spots and faculae are very sparse, although occasionally a 

 spotlet or a few faculic markings may be seen. The positions 

 of the Sun's axis, centre of the disc, and heliographic longitude 

 of the centre are given in the following table : — 



A suitable diagram, for this period, for the projection of the 

 solar disc is shown on page 310 of last month's issue. 



The Moon : — 



OccuLT.^TiONS. — The only naked eye star occulted during 

 the present month and visible from Greenwich, is the 5i mag- 

 nitude star 43 Ophiuchi. The occultation occurs on Septem- 

 ber 1st, disappearance being at 7.58 p.m.. and re-appearance 

 at 8.4 p.m. 



THE PLANETS. 



Mercury is in inferior conjunction with the Sun on the 9th. 

 .^fter this date the planet is a morning star in Leo and is at 

 greatest westerly elongation of 17^" 52' on the 25th, on which 

 date he rises at 4 a.m., or nearly two hours in advance of the 



Sun. The elongation is thus a somewhat favourable one for 

 seeing the planet. 



Venus :^— 



Venus is in inferior conjunction with the Sun on September 

 15th, and throughout the month is unobservable, as she 

 appears too near the Sun. 



NL\RS : — 



Mars is an evening star, rising N,E, by East at 9,30 p.m.. on 

 the 1st, and at S p.m. on the 30th. The planet appears 

 between .Aldebaran and the Pleiades, somewhat nearer the 

 former. 



The planet is becoming more favourably placed for observa- 

 tion and is increasing in brightness, the apparent diameter of 

 the disc increasing from 11" -4 to 14"-0 during September. 



As seen in the telescope the planet appears gibbous, l"-6 

 of the disc being unilluminated. The south polar cap is \isible 

 and appears fairly bright ; but other markings are difficult to 

 delineate in telescopes of three or four inches aperture, even 

 if powers of two hundred or three hundred be used, 



Jupiter : — 



Jupiter is an evening star setting \\'.S.\\'. at 8.45 p.m., on 

 the 1st and at 7 p,m, on the 30th, The planet is very little 

 observable as he is rather low down at sunset, and is soon 

 lost to view in the evening ha^e. 



No satellite phenomena are observable, as the planet appears 

 in too bright a portion of the sky when any of the transits or 

 eclipses occur. 



The configurations of the Satellites as seen in an inverting 

 telescope and observing at 7 p.m. are as follows : — 



360 



